Terminal construction for electron discharge devices



p 1950 H. R. JACOBUS 2,522,517

TERMINAL CONSTRUCTION FOR ELECTRON DISCHARGE DEVICES Filed May 8, 1948 IN VEN TOR. HKiJKF/FflYMOA D #160505 A T'TOZP/VE Y Patented Sept. 19, 1950 TERMINAL CONSTRUCTION FOR ELECTRON DISCHARGE DEVICES Herbert Raymond Jacobus, White Plains, N. Y.,

assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application May s, 1948, Serial No; 25,896

, 1. Claim.

The present invention relates to the construction of electron discharge devices, and in particular, to grid ring constructions of the kind mwhich a'metallic conductor is sealed between two glass portions of the envelope of such devices,

In electron discharge devices of the multielectrode type used at very high frequencies, it i's'often desirable to have the grid or other electrode brought out in the formof an annular conductor. Various methods of constructing tubes in this form are known. For example, the grid may be mounted on a thin copper disc sealed into the glass of the bulb. This method involves a rin shaped copper member with the top and bottom peeled back to provide feathered flanges easily sealed into the ends of cylindrical walls of glass. A disadvantage of this method is that while one edge is being sealed to the glass the other thin edge may be burned, and to prevent this happening it is. often necessary to machine and feather the second copper edge after the first glass seal has been made. It has also been proposed that in order to eliminate the machining operation and at the same time prevent burning of the second edge, two separate metallic tubular members may be used each having a transverse section which may be placed back to back, and secured together in a vacuum-tight joint by brazing.

While the foregoing constructions are mechanically and electrically satisfactory, they nevertheless are expensive and difficult to manufacture. It is, accordingly, an object of this invention to provide a grid ring construction which is simple, rugged and relatively inexpensive to make. This is accomplished by simplifying the method of construction of the grid ring which consequently results in a reduction of the amount of time, labor and material which were heretofore believed necessary in the construction of grid rings for electron discharge devices.

The grid ring in this invention is formed by means of two tubular members of metal, such as Kovar or the like, each having a cylindrical portion and a, radially extending annular portion at one end of the cylindrical portion. The annular portion at one member extends outwardly of the cylindrical portion while the annular portion of the other extends inwardly of the cylindrical portion. The cylindrical portions of the two members are preferably of different diameters so that one telescopes within the other. By positioning one within the other and then 2 3 welding or brazing the two parts together a grid ring is formed having an inwardly extending portion to which a grid may be secured and an outwardly extending annular portion for circuit connection. The ends of the cylindrical portions are either feathered or rounded for sealing connection with the glass envelope.

The above mentioned and other features and objects of this invention and the matter of attaining them will become more apparent, and the invention itself will be best understood, by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is an exploded view of the grid ring showing in perspective the parts thereof;

Fig. 2 is a view in elevation of the parts of Fig. 1 assembled with a portion thereof shown in section; and

Fig. 3 is a bottom view of the grid ring construction.

Referring to Fig. l, the component parts of the grid ring are shown in exploded view illustrating the way the components are assembled. The grid ring proper comprises two members I and 2, the member I having a cylindrical portion 3 and an outwardly extended annular portion 4, while the member 2 comprises a cylindrical por tion 5 with an inwardly extended annular portion 6. The cylindrical portion 5 is preferably made of smaller diameter than the cylindrical portion 3 so that it may be received in telescoping relation in the cylindrical portion 3, as best shown in Fig. 2. Copper rings I and 8 are provided for reception in the crevices formed between the two telescoping parts, the copper wire being utilized as a flux during the welding or brazing together of the two cylindrical portions. While two such rings are shown, one, of course, may be suflicient to provide a sealed connection between the two members.

The outer edges 9 and Ill of the cylindrical portions 3 and 5 are preferably rounded or smoothed down to remove sharp edges. Kovar thus smoothed is easily beaded with glass as indicated at H and I2 by bringing the Kovar and the glass to a corresponding temperature where the glass is softened to nearly a molten condition. The Kovar and glass having substantially the same coeflicient of expansion makes a good seal which will withstand heating and cooling without breaking. The glass beading may be applied to the cylindrical portions of members I and 2 prior to or after the telescoping thereof. The inner extended annular portion 6 of the member 2 is preferably fluted or corrugated, as indicated at l3 to strengthen it for the support of the grid electrode, which may be mounted thereto at openings H. The outwardly extended flange or annular portion 4 provides for electrical connection adjacent the side of the tube envelope.

While particular reference has been made to the selection of Kovar for the members I and 2, it should be clearly understood that other materials may be employed, such for example, as copper. Where copper is employed the edge of the cylindrical portion may preferably be feathered for glass beading purposes.

From the foregoing it will be clear that the grid ring according to the present construction is easily made by stamping or pressing sheet stock into the shapes of members I and 2, and since one is capable of telescoping into the other, a sturdy ring construction can thereby be produced. By welding or brazing the parts together with copper flux a vacuum seal is insured. While the members I and 2 are particularly shaped for the manufacture of an annular grid ring, it will be clear to those skilled in the art that they may be made into other telescoping shapes and may be utilized in devices other than electron discharge tubes wherever a metallic connection is desired between two walls of glass or other insulating material.

- While I have described above the principles 4 of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation of the scope of my invention.

I claim:

An electron discharge device having an envelope including tubular glass sections and an intervening tubular metal section, said intervening metal section comprising two tubular metal members each having a cylindrical portion sealed at one end to one of said glass sections and terminating at its opposite end in a radially extending flat annular portion, the annular portion of one of said members extending outwardly of the cylindrical portion and the annular portion of the other of said members extending inwardly of the cylindrical portion, and the cylindrical portions of the two tubular metal members being of different diameters with one telescoping into the other.

HERBERT RAYMOND JACOBUS.

REFERENCES CITED The following references are of record in the 

